JPS63170807A - Manufacture of non-reducing dielectric ceramic - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

Detailed Description of the Invention (Industrial Application Field) The present invention relates to a method for manufacturing non-reducible dielectric ceramics, and particularly relates to a method for manufacturing non-reducible dielectric ceramics used as dielectric materials such as multilayer capacitors. .

(Prior art) Conventionally, when manufacturing a multilayer capacitor, a plurality of dielectric green sheets, each of which has a metal powder layer that will become an internal electrode by printing on its top surface, are stacked, crimped, and integrated. , a process of firing the integrated product is adopted.

(Problems to be Solved by the Invention) Conventional dielectric ceramics have the property that when fired under low oxygen partial pressure, they are reduced and their specific resistance deteriorates significantly. For this reason, the firing is performed under high oxygen partial pressure such as in air.
For example, it was carried out at a high temperature of 1.300°C or higher.

Therefore, noble metals such as palladium and platinum must be used as materials for the internal electrodes that can withstand such heat treatment conditions, which is a major hindrance to increasing the capacity and lowering the price of manufactured multilayer capacitors. was.

Therefore, in order to solve the above-mentioned problem, the present inventors
For example, we created dielectric porcelain that does not reduce even when fired under low oxygen partial pressure and has a high specific resistance so that base metals such as nickel can be used as materials for internal electrodes. As this dielectric ceramic, Japanese Patent Publication No. 56-46641 describes ((Ba, Ca)O) - (Ti, Zr
) A solid solution consisting of Ox is disclosed. However, in the dielectric porcelain manufactured by the manufacturing method disclosed in this publication, since the porcelain composition forms a uniform solid solution during the sintering process, each Curie point is single;
The temperature change rate of its dielectric constant was large.

As a result of diligent efforts, the inventors of the present invention have found that the temperature change rate of the dielectric constant can be reduced by not completely dissolving ZrO□, CaO, etc. into BaTi0° during the sintering process.

Therefore, the main object of the present invention is to exhibit a high resistivity without being reduced and turned into a semiconductor even when fired in a non-oxidizing atmosphere, and to have a high dielectric constant, and also to It is an object of the present invention to provide a method for manufacturing non-reducible dielectric ceramics that can manufacture non-reducible dielectric ceramics with a small rate of change.

(Means for Solving the Problems) The present invention is based on BaTiO3 which is calcined and pulverized.
, CaTiOs and CaZrOs, BaTi0+ is 82.0 to 93.0 mol%, CaTiOx is 6.0 to 1
4.0 mol% and CaZrO3 in the range of 1.0 to 8.0 mol% are prepared as the main component, and manganese oxide, barium oxide and dioxide are added as subcomponents to 100 mol parts of the main component. Silicon, respectively, Mn0t
, MnO, converted to BaO and 5ift, is 0.
1 to 4.0 mol parts, BaO 0.2 to 4.0 mol parts,
and adding SiO
This is a method for manufacturing non-reducible dielectric ceramics.

(Effect of the invention) According to the invention, for example, 1,2
Even when fired at a temperature of 70 to 1,360°C, it does not reduce and become a semiconductor, but exhibits a high specific resistance of 10"Ω1 or more, has a high dielectric constant of 3.000 or more, and -55
It is possible to produce a non-reducible dielectric ceramic whose temperature change rate of dielectric constant is as small as 115% to +15% over a wide temperature range of 125°C to 125°C.

Further, according to the embodiment of the present invention, the dielectric loss is as small as less than 1.00%, and the dielectric constant in the temperature range of -25°C to +85°C is based on the dielectric constant at a temperature of +20°C. Excellent properties were obtained, with a temperature change rate of less than 10% of that of soil.

Therefore, it is possible to produce a non-reducible dielectric ceramic that satisfies all of high permittivity, low dielectric loss, and good permittivity-temperature characteristics, and is extremely useful as a dielectric material for small, large-capacity capacitors. . Moreover, if this non-reducible dielectric ceramic is used as a dielectric material for a multilayer ceramic capacitor, for example, an inexpensive multilayer ceramic capacitor can be obtained in which internal electrodes are made of a base metal such as nickel.

The above objects, other objects, features and advantages of the present invention will become more apparent from the detailed description of the following embodiments.

(Example) First, BaC0z and Tie are weighed in a ratio to form BaTi0:+, mixed thoroughly in a ball mill, and this mixture is calcined at 1200°C for 1 hour. Shattered.

Similarly, CaTiO3 powder calcined and finely ground from CaC0* and TiO□ and CaZrO3 powder calcined and finely ground from CaC0 and ZrO□ were obtained, respectively.

The X-ray diffraction images of these powders confirmed that these powders had uniform crystallinity.

Each powder of BaTiO3, CaTiO3 and CaZrO3 thus obtained and Mn01. BaQ and 5iO1 were weighed so as to obtain a dielectric having the composition ratio shown in Attached Table 1. In Table 1, numerical values of composition ratios outside the scope of the present invention are underlined.

Furthermore, 5% by weight of a vinyl acetate organic binder was added to this weighed raw material, wet mixed, and then evaporated.

A powder was obtained through drying and sizing steps. Then, this powder was molded to a diameter of 101° and a thickness of 1 fl at a pressure of 2000 kg/cffl to obtain a molded product.

This molded product was placed in an alumina box with zirconia powder as a bed powder, and heated at 1°270°C to 1,400°C in a reducing gas atmosphere with a volume ratio of Hz/Nt of 3/100.
An element was obtained by firing at a temperature of .degree.

Applying In-Ga alloy to both sides of the obtained element,
Electrodes were formed and each sample was obtained.

Then, the dielectric constant ε and dielectric loss tan δ of each sample.

The electrical characteristics of the temperature change rate of dielectric constant and specific resistance were measured under the following conditions.

The dielectric constant ε and the dielectric loss tan δ were measured at a frequency of 1 kHz and a temperature of 25°C.

The temperature change rate of the dielectric constant is the temperature change rate of the dielectric constant (ΔC/Czs) in the temperature range of -55℃ to +125℃ based on the dielectric constant at a temperature of +25℃, and the dielectric constant at a temperature of +20℃. The temperature change rate (ΔC/C, .) of the dielectric constant in the temperature range of −25° C. to +85° C. as a reference was measured.

The specific resistance is DC, 500V at 25°C.
Measurements were taken after applying the voltage for a minute.

The above measurement results are shown in Attached Table 2. In Table 2, numerical values with poor characteristics are underlined. In this case, the dielectric constant ε is less than 3,000, the dielectric loss tan δ is 1% or more, and the temperature change rate of the dielectric constant (ΔC
/C□) outside the range of -15 to +15%, and temperature change rate of dielectric constant (ΔC/C,.) -1
Those outside the range of 0 to +10%, for specific resistance, lO
Those without grooves of Ω·cm were shown as having poor characteristics.

In other words, as in sample number 4, BaTiOs is 82 mol%.
If the dielectric constant is less than
If TiOs exceeds 93 mol %, the temperature characteristics of the dielectric constant deteriorate.

In addition, when CaTiOs is less than 6 mol% as in sample numbers 1 and 6, the temperature change rate of the dielectric constant exceeds 115%, and when CaTiOs exceeds 14 mol% as in sample number 3, the dielectric constant is small. Become.

When CaZrO3 is less than 1 mol% as in Sample No. 2, the temperature change rate of the dielectric constant exceeds -15%, and when CaZrO3 exceeds 8 mol% as in Sample No. 5, the dielectric constant becomes small.

On the other hand, if MnO2 is less than 0.1 mol part as in Sample No. 15, the dielectric constant becomes small and the temperature characteristics of the dielectric constant become poor, and if MnO2 exceeds 4 mol part as in Sample No. 18, the dielectric constant decreases and the temperature characteristics of the dielectric constant deteriorate. The ratio becomes small, less than 2,000.

In addition, when BaO is less than 0.2 mol part as in sample number 19, the specific resistance decreases due to reduction firing and the temperature change rate of the dielectric constant increases, and as in sample number 22, BaO
If aO exceeds 4 mole parts, the dielectric constant will be low and the sinterability will be poor.

If the amount of Sin is less than 0.1 mole part as in Sample No. 23, the sinterability decreases, the dielectric constant decreases, and the temperature change rate of the dielectric constant increases, and as in Sample No. 26, Sin, If it exceeds 3 molar parts, the dielectric constant becomes small and the temperature change rate of the dielectric constant becomes large.

In addition, as a reference example, as disclosed in Japanese Patent Publication No. 56-46641, it was prepared without passing through each component of BaTiOs, CaTiO3 and CaZr0:+ (
(Ba, Ca)0) +e ・(Ti+ Zr)O
The composition of the solid solution consisting of z, its dielectric constant, dielectric loss, temperature change rate of dielectric constant, and specific resistance are shown in Appendix 1.
It is shown as sample number 28 in Attached Table 2. The composition and electrical characteristics of an example of the present invention corresponding to sample number 28 are shown as sample number 27 in Attached Tables 1 and 2. In addition, in Japanese Patent Publication No. 56-46641, no subcomponents were contained, but in sample No. 28, 0 g of Mn and 1 mole part of SiO□ were each added as subcomponents.
It was added in an amount of 2 moles.

As is clear from comparing the results of sample number 27 and day 2, sample number 28 has a single solid solution, has a low dielectric constant, and has a single Curie point, so it has the disadvantage that the rate of change in dielectric constant with temperature is large. However, on the other hand, it can be seen that sample number 27 within the scope of the present invention exhibits a high dielectric constant and a flat temperature change rate of the dielectric constant.

Furthermore, as is clear from Attached Table 2, according to the present invention,
The dielectric constant is 3.000 or more, the dielectric loss is less than 1.00%, and the temperature change rate of the dielectric constant in the temperature range of -55℃ to +125℃ based on the dielectric constant at +25℃ is ± 15%, and the temperature change rate of the dielectric constant in the temperature range of -25°C to +85°C is less than ±10% based on the dielectric constant at +20°C. I understand.

Patent applicant Murata Manufacturing Co., Ltd. Agent: Patent Attorney Oka 1) Zenhiro (1 other person)

Claims (1)

[Claims] BaTiO_3 and CaTi each calcined and pulverized
O_3 and CaZrO_3, BaTiO_3 is 82.0 to 93.0 mol%, CaTi
O_3 is 6.0 to 14.0 mol%, and CaZrO_
3 was blended in the range of 1.0 to 8.0 mol% as the main component, and to 100 mol parts of the main component, manganese oxide, barium oxide, and silicon dioxide were added as subcomponents, respectively. MnO_
2. In terms of BaO and SiO_2, MnO_2 is added in the range of 0.1 to 4.0 mol parts, BaO is 0.2 to 4.0 mol parts, and SiO_2 is added in the range of 0.1 to 3.0 mol parts. A method for producing non-reducible dielectric porcelain, which further comprises firing a mixture of the main component and the subcomponent added thereto.